Optical Spectrometers and Multispectral Sensors in Consumer Goods and Wearables

In the past twenty years optical spectrometers have shrunk dramatically in size, giving us successively laboratory-portable, toaster-sized, instruments; cordless-drill-sized portable instruments for use in the field; and onto spectrometers the size of a computer mouse or deck of cards. The latest development in portable spectroscopy is the availability of very low-cost multispectral sensors, the size of computer chips, leading to the possibility of embedding them into consumer goods. Multispectral devices can be produced in volume via semiconductor and optical coating techniques, at very low cost - less than $10 each. The width of absorption bands in the visible and near-infrared regions for condensed phase samples imply that an instrument with a small number of resolution elements will be able to perform routine (especially qualitative) analyses, and that spectral range is a more important parameter than spectral resolution. Multispectral sensors can now not only be incorporated into ‘white goods’ like washing machines and dryers, but also into ‘fitness’ products like smart watches and sports watches, and as photonic miniaturization increases, into ‘wearables’ like smart rings, providing the user with health information. Silicon photonics and photonic integrated circuits (PICs), produced en masse using semiconductor manufacturing techniques, are the ideal next step. This paper surveys the field, and highlights some ‘smart’ consumer device possibilities from cosmetics to toothbrushes to toilets.